1. Field of the Invention
The present invention relates generally to an electrically powered seat lifter for a seat assembly to be installed in an automotive vehicle.
2. Description of the Background Art
In the advanced automotive technologies, a seat assembly can be adjusted to various positions utilizing electrically powered servo systems. For instance, a seat back recliner, a seat slide, and so forth often employ such electrically powered servo systems for convenience of adjustment. Similarly, some automotive seat assemblies employ a seat lifter with an electrically powered servo system for adjusting a height position of the seat cushion. The electrically powered servo system for the seal lifter is composed of a plurality of components, such as an electric motor, a gear train and so forth. In general, these components of the servo system are installed beneath the seat cushion.
On the other hand, in the recent days, some types of vehicles require a lower seat position for providing a sporty drive feeling. In order to answer such requirement, the seat cushion is required to be oriented at a lower elevation, at least at the lowermost lift position. The components of the servo system of the seat lifter may then servo to border or restrict a magnitude of lowering of the seat cushion height level. Therefore, for a power seat lifter which incorporates the electrically powered servo switch, the range to lower the seat cushion height level has been strictly limited so as to make it difficult to fully answer the requirement for the lower seat cushion position.